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Multiresonance thermally activated delayed fluorescence (MR-TADF) emitters are excellent candidates for high-performance organic light-emitting diodes (OLEDs) due to their narrowband emission properties. However, the inherent mechanism of regulating the rate of intersystem crossing (ISC) is ambiguous in certain MR-TADF skeletons. Herein, we propose a mechanism of accelerating ISC in B/S-based MR-TADF emitters by peripheral modifications of electron-donating groups (EDGs) without affecting the narrowband emission property. The long-range charge transfer (LRCT) stems from the introduced EDG leading to high-lying singlet and triplet excited states. The ISC process is accelerated by the enhanced spin-orbital coupling (SOC) between the singlet short-range charge transfer (SRCT) and triplet LRCT manifolds. Meanwhile, the narrowband emission derived from the MR-type SRCT state is well retained as expected in the peripherally modified MR-TADF emitters. This work reveals the regulation mechanism of photophysical properties by high-lying LRCT excited states and provides a significant theoretical basis for modulating the rate of ISC in the further design of MR-TADF materials.
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http://dx.doi.org/10.1021/acs.jpclett.4c00608 | DOI Listing |
J Phys Chem Lett
September 2025
Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States.
Carbon dots (CDs) represent a new class of nontoxic and sustainable nanomaterials with increasing applications. Among them, bright and large Stokes-shift CDs are highly desirable for display and imaging, yet the emission mechanisms remain unclear. We obtained structural signatures for the recently engineered green and red CDs by ground-state femtosecond stimulated Raman spectroscopy (FSRS), then synthesized orange CDs with similar size but much higher nitrogen dopants than red CDs.
View Article and Find Full Text PDFJ Am Chem Soc
September 2025
Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States.
Coherent electron spin states within paramagnetic molecules hold significant potential for microscopic quantum sensing. However, all-optical coherence measurements amenable to high spatial and temporal resolution under ambient conditions remain a significant challenge. Here we conduct room-temperature, picosecond time-resolved Faraday ellipticity/rotation (TRFE/R) measurements of the electron spin decoherence time in [IrBr].
View Article and Find Full Text PDFJ Phys Chem Lett
September 2025
School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, People's Republic of China.
Inverted quantum dot light-emitting diodes (QLEDs) show great promise for next-generation displays due to their compatibility with integrated circuit architectures. However, their development has been hindered by inefficient exciton utilization and charge transport imbalance. Here, we present a strategy for regulating charge-exciton dynamics through the rational design of a multifunctional hole transport layer (HTL), incorporating polyethylenimine ethoxylated (PEIE) as a protective interlayer in fully-solution-processed inverted red QLEDs.
View Article and Find Full Text PDFJ Chem Theory Comput
September 2025
Department of Chemistry, University of California, Berkeley, California 94720, United States.
We investigate the ability of Aufbau suppressed coupled cluster theory to act as a post-linear-response correction to widely used linear response methods for electronically excited states. We find that the theory is highly resilient to shortcomings in the underlying linear response method, with final results from less accurate starting points nearly as good as those from the best starting points. This pattern is especially stark in charge transfer states, where the approach converts starting points with multi-eV errors into post-linear-response results with errors on the order of 0.
View Article and Find Full Text PDFAdv Mater
September 2025
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
Helicene-based circularly polarized luminescence (CPL) materials suffer from severely low color purity in circularly polarized organic light-emitting diodes (CP-OLEDs). Here, a novel molecular engineering strategy is introduced by replacing helicene containing continuous fused benzene rings with a multiple resonance (MR) framework comprising discontinuous fused benzene rings. This approach effectively suppresses high-frequency C─C bond stretching vibrations and enhances short-range charge transfer, enabling high color purity, CPL activity, and efficient thermally activated delayed fluorescence (TADF).
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